A latch bolt for a car door includes one or more energy-absorbing buffers to lower noise during operation of the latch mechanism of the latch bolt. The energy-absorbing buffers can be located in a variety of positions on the latch bolt, depending on what type of impact the energy-absorbing buffers are intended to absorb energy from. Energy-absorbing buffers are commonly located to absorb some of the impact between the latch bolt and an open latch abutment as the latch bolt moves, under spring bias, from a closed position to an open position. At the closed position, a striker mounted on the door frame is retained by the latch bolt. When the latch bolt moves into the closed position, a pawl moves past a first safety abutment of the latch bolt and is spring biased to engage a closed abutment of the latch bolt to maintain the latch bolt in the closed position. Energy-absorbing buffers are sometimes located to absorb some of the impact between the first safety abutment or the closed abutment of the latch bolt and the pawl.
An energy-absorbing buffer has also been provided to absorb energy from over-travel of the latch beyond the closed position, which can occur when the closure is slammed shut. The momentum of a closure shutting is normally much greater than the momentum of the latch bolt springing open or of the pawl engaging with the latch bolt. Therefore, an energy-absorbing buffer designed to absorb impact from over-travel needs to be able absorb much more energy than the energy-absorbing buffers described above.
Known energy-absorbing buffers (such as described in EP 0995879) include an aperture or cavity in the latch bolt which collapses under impact. These single cavity based buffers have difficulty absorbing large impacts and therefore only have limited use as over-travel buffers. The single cavity based buffers rely solely on deformation of the buffer to absorb energy.
To absorb the additional energy, over-travel buffers may have cavities of a more complex shape and/or include additional cavities (such as described in EP 1136640). These buffers are better suited for use as over-travel buffers, but still rely solely on absorbing energy by deformation. Consequently, they are not ideal in certain applications.